Create one more Model class like below
public class NewModelClass{
public int SelectedId{get;set;}
public IEnumerable DocumentTypes { get; set; }
}
public ActionResult Save(NewModelClass objNewModelClass){
var selectedId=objNewModelClass.SelectedId;
}
Change your dropDown like below by surrouding Html.BeginForm in View
@model NewModelClass
@{
ViewBag.Title = "Index";
}
@using (Html.BeginForm("YourControllerName","Save",FormMethod.Post))
{
@Html.DropDownListFor(model => model.SelectedId,DocumentTypes, "--select--", new { @class = "ddSelect" })
<input type="submit" value="Click"/>
}
Hope this helps